Control device



v H. E.'MALONE K April s, 1943./

CONTROL DEVICE Filed March 2|, 1940 2 Sheets-Sheet 1 H l INVNTOR. Hamer'ENEZDHE BY W%'ATTORNEY.

`Apwil 6, 1943.

H. E, MALoNE y CONTROL DEVICE 2 Sheets-Sheet 2 Filed March 2, i940INVETOR. Hamer E. Melun e BY @$7 W ATTORNEY.

Paten-ted Apr. 6, 1943 CONTROL DEVICE Homer E. Malone, Milwaukee, Wis.,assignor to Perfex Corporation, Milwaukee, Wis., a corporai tion ofWisconsin Application March 2, 1940, Serial No. 321,822 22 claims. (ci.zoo- 138) This invention relates in general to control devices but moreparticularly to automatic control devices for use in air conditioningsystems, and the broad object of the invention is to provide an improvedcontrol device embodying electric switching. mechanism operativeresponsive to temperature changes.

In air conditioning systems it is customary to provide a heating plantor furnace for'warming the air in a space to be heated and in some casesto provide a means for circulating the heated air. In order to controlthe operation of the heating plant within certain limits and to maintainthe space at a comfortable temperature a room thermostat is usuallyprovided to regulate thegeneratio'i'i of heat from the furnace'. Tofurther insure greater uniformity of temperature in the space beingheated and to safeguard vagainst excessive temperatures in the heatingplant, it has been customary to supple- I elements is obtained. i

ment the room thermostat with a control means commonly called a iimitcontrol, which is arranged to respond directly to the temperature of thefurnace and may b located -upon a warm air duct or the bonnet of thefurnace. It is likewise desirable that the heated air be forced orcirculated to the space to be heated and for this purpose an additionalcontrol device is located sovas to be responsive to the furnacetemperaiure to prevent the circulation of the air until it reaches apredetermined temperature. In eertain instances it may also be feasibleto -control ,lthevaircirculating means in accordance with differentvspeeds `at different temperatures to` more uniformly regulate the spacetemperature.

f regulate the air conditioning `system in a more reliable andsatisfactory manner.

A further object is to provide a control device arranged for use as acombination limit control and aircirculating control,l or alternativelyas a. control device for operating the air circulating means atdifferent speeds in response to differcnt temperature. values.

It is an additional object to provide a control device having improvedcam means'for actuating the switching mechanism together with simi plemeans for adjusting the temperature settings and differential operationof the cam means. Y

Another object of theinvention is to provide an automatic thermostatic'control device arranged to be manually operated toactuate the aircirculating means in the summer months for the purpose, of cooling aroom for example.

With the foregoing and other objects inview the invention consists inthe construction, arrangement and combination of the variousparts andelements of the control device, whereby the objects contemplated areattained, as hereinafter more fully.,r set forth, pointed out in theclaims, and illustrated in the accompanying sheets of drawings. Apreferred embodiment of the invention is disclosed in the drawings inwhich: f

Fig. 1 is a side view, partiallyin section, oi a control deviceembodying the invention;

Fig. 2 is a full front view of the control dcvice with the cover orhousing removed and showing the control in its operated or runningposition;

Fig. 3 is a view taken along the line 3--3 in Fig, 2 showing theswitching mechanism;

Fig. 4 is a cross-sectional fragmentary view taken along the line 4--4of Fig. 2 showing the switch operating'cam elements;

Fig. 5 is a perspective view of one of the switching mechanisms;

Fig. 6 is a view showing in extended 'perspective relationship thevarious elements mounted on the control operating shaft;

Fig. '7 is a view taken along the line 1-1 of Fig. 1 showing one set ofcam discs and also a modified form of the switching mechanism;

Fig. 8 discloses a schematic circuit arrangement showing an adaptationof the control device for controlling the various speeds of an aircirculating means; while v y Fig. 9 is a schematic circuit arrangementshowing the use of the control device as a combination limit control andair circulating control means.

The control device in its essential elements comprises primarily a flatmetal base plate |l having a conduit attaching bracket l2 suitablysupported atits lower end as shown in Figs. 1 and 2. Extendingrearwardly from the base plate II is a metal supporting tube i3 suitablyattached as by a staking operation to the base plate l I as shown inFig. 4. The tube I3 serves, in the well-known manner, to support, bymeans of an adjustable flange (not shown), the complete control devicein position upon the bonnet or warm air duct of a furnace, or otherselected location. The open end of the tube I3 has a bracket element I4secured thereto as by a rivet I5. The bracket I4 serves as a support andbearing for a physical condition responsive means shown here in the formof a coiled bimetallic helix or thermal element I6. In the use of thedevice, the bimetal element IS extends within the warm air duct orfurnace so as to be subjected to lthe varying temperature changesproduced within the furnace. The bimetal element I5 is supported andsecured at one end by a screw I1 threaded into bracket I4. The other endis fastened by a screw I8 to the end of a rotatable shaft or torsion rodI9 which is arranged to extend axially through the bimetal element I5and supporting tube I3 to the front side of supporting base II. Abearing sleeve member 2I suitably secured to supporting plate II, asshown in Fig. 4, serves to guide the rod I9 and support the same at oneend. The bracket I4 performs a similar function intermediate the endsofthe rod I9. In order to limit outward or forward axial movement ofshaft orrod I3,a stop washer 22 and a cotter 23 on the rod are adaptedto contact the bracket I4. The rod I9 is rotatiyely actuated by thebimetallic helix I 5 n conformity with changes in the temperatureapplied to the bimetallic helix I6. A suitable metal cover or housing 24is provided for enclosing the control mechanism on the front of the baseplate llas shown in Fig. 1. This cover 24 is secured in position on thebase II by means of thumbnuts 25 threaded into L-shaped brackets 26 inturn secured to the base.

Arranged in spaced relationship to the base plate II is a panel 21 madeof insulated material. This panel 21 is supported by means of a seriesof spacer studs 28 into which thepa'nel attaching screws 29 arethreaded. At the bottom end of the insulating panel 21 there issupported a series of binding posts 3I for the attachment of theconnecting wires (not shown) which pass through the opening in conduitbracket I2. In order to segregate the attached Wires from the electricalswitching equipment arranged above it a barrier'plate 32 made ofinsulating material is suitably staked to the panel 21 in an upright orprojecting position. To further electrically insulate the electricalequipment and the wiring arranged under the panel 21, a thin flat wall33 of. insulating material is arranged directly on top or outer face ofthe supporting base II.

The operating mechanism .for controlling the switching mechanism issupported upon the forward or outer end portion of the torsion rod I9which extends from the front of the supporting base II as shown moreclearly in Figs. 4 and 6. One of the elements of this controllingmechanism comprises a tubular sleeve or hub member 34 arranged with anaxial bore adapted to fit over the end of the shaft I9. The hub member34 is rigidly secured to the end of the shaft I9 by means of a pair ofscrews 35 and 35 threaded into the hub and engaging or tightly abuttinga reduced portion of the shaft. A hollow knob or manually controlledmember 31 is arranged on the end of the hub member 34 and is providedWith a fiat nger engaging portion 38 for manually rotating the shaft I9when desired, as

will be pointed out. The end of the finger p0rtion 38 protrudes throughthecover 24 and is provided vvith an indicating arrow 39 at its frontable indicia 40 on the cover front, the rotated position of shaft I9 andtherefore thetemperature of the bimetal I5 at any particular time.

Secured as by riveting to the other end of hub member 34 is a flat disc4I having a notch 42 cut in its periphery. The notch 42 is adapted-toengage a lug or pin 43 which is rigidly moimted on the panel 21. Theengagement of the notch 42 with the pin 43 is brought about when theshaft I9 is manually rotated and pushedv inward bythe knob 31 as will bepointed out hereinafter.

Referring particularly now to Fig. 6 a plurality of elements arearranged in sequential order as shown upon the outside of hub member.The rst of these elements comprises a stiff compression spring 44encircling the portion 45 of the hub 34. A fiat metal bearing washer 44is then placed upon the portion 45 after which the "ofr cam member ordisc 41 is placed on the hub. The off cam 41 is provided with anintegral extension or adjusting arm having suitable indicia stampedthereon as shown. An op erating cam surface 43 is formed on theperiphery of the cam member 41. Extending from one side of the camsurface 43 a low retaining surface 5I is formed on the cam periphery,while extending from the other side of cam surface 4I a high retainingsurface 52 is provided. A thin paper washer 53 and a fiber or corkwasher 54 are next arranged on the hub. These two elements togethercomprise a frictional resistance means which tends to frictionallyrestrain rotary movement of the off cam member 41 on the shaft 45against the compression of spring 44 when a manual adjustment of the cammember ls being made.

The next element in order mounted upon the hub 34 is the on cam memberor disc 55 having an integral adjusting arm 55 extending therefrom whichis supplied with suitable indicia as shown. The cam member 55 isprovided with a circulator slot 51 having a cam surface 5l formed on theside of the slot and an inner retaining surface 53 and an outerretaining surface 60 extending from opposite sides of cam surface 55.The next elements placed upon the shaft comprise a paper washer 6I and aber washer 52 which togethe; provide frictional resistance to the rotaryadjustment of cam member 55 against the pressure spring 44.

A'scale member or indicating disc comprising a flat segment member B3 isnext placed upon the hub member 34. Instead of being loose and freelyrotatively positioned upon the hub member, as are the other aforesaidelements, the

scale member 53 is rigidly and firmly secured to the hub member 34 bymeans of the cooperating knurled surfaces 54 and 55 on the hub 34 andthe scale 63, enabling the scale plate 53 to be forced onto the hub witha drive fit. The scale member 63 is provided at its periphery withgraduated markings 66 comprising suitable temperature indications whichcooperate with the markings on the adjusting arms 48 and 55 to indicatethe adjusted settings of the cam members 41v and 55. At one end of thescale' 55 an integral stop member 51 is provided and a sim ilar stopmember 68 is arranged at the other end of the scale. These stops limitthe adjusting range of the adjustlngarms 48 and. 55. A slot 69 is cut inthe scale member 63 for a purposeA which will be hereinafter pointedout.-

Following the foregoing elements in the assembly on the hub member 34, athird set of surface which indicates in cooperation with suit`75Ufriction means comprising a, pape-r washer 1| member 13 isadditionallyv provided with cam netic bridging bar or member 92 ispivotally surfaces 16 and 11 oppositely disposed' from each other andformed on the opposite sides of a single circular slot 18 eut in thecam.v Inner and outer retaining surfaces form the side walls of slot 18and extend from each side of the l cam surfaces 16 and 11. A stop screw19 is arranged to be threaded into either one of two or more screw holesin the cam disc 13 and extends through the rear oi the cam member tocooperate with the end of the slot 89 in the scale plate 63 toadjustably limit the adjustment of cam member 13 beyond a certain range.

A compression spring 80 is next placed upon the hub member 34 and exertsits effort against the side of cam member 13 to yieldingly'urge ittoward the front'side of thescale member 63 in the same manner thatcompression spring 44 yieldingly urges or` presses both of thecammembers 41 and 5-5 toward the rear side of scale member 63; After all ofthe foregoing elements have been positioned inthe successive order uponthe hub 34, as shown in the assembled relationship in Fig. 4, the knobmember 31 is placedoverrthe end of the hub 34 to engage the end of therotatable shaft I9 so that the complete assembled unit is securely andrigidly attached to the end of the operating shaft I9.

'Ihe various cam surfaces 49,y 58, 16 and 11 are arranged to operate andeffect the. various control or switching operations for which thecontrol device has been designed. To perform trol elements or contactsets |03 and |94. Ar-

supported as shown clearly in Fig. 3. A flexible arm 93 is suitablyriveted as shown to one end of the rigid bridging bar 92. A pairof'control means shown as movable contact elements 84` and 95 are`arranged upon opposite ends of the rigid bar 92 and flexible arm 93.The movable contact 95 is secured to the end of flexible arm 93 inspaced relationship to the adjacent end of rigid bar 92 while themovable contact 94 is clamped rigidly with the flexible arm 98 to theother end of the rigid bar 92. A pair of control elements shown as fixedcontact points or studs 96 and 91 are adjustably supported in turnedupbrackets 98 and 99 which are in turn secured to and supported as by thescrews shown, upon f the insulating panel 21. The fixed contact points9S and 91 are arranged in cooperable relationship with the movablecontact points 94 and 98, respectively.

Also secured to the lower end of the insulating arm 86 and spacedopposite the armature 89 is a similar armature IilI. Armature IUIsupports a pivot pin |92 which in turn pivotally carries a control meansor switching mechanism designated as B which is similar to that carriedby armature 89 and lwhichincludes the pairs of conranged between the twoarmatures 89 and |8| and with its poles projecting through the panel 21and in cooperative magnetic relationship with the armatures, is apermanent magnet |85. As seen in Fig. V3, magnet |05 i's held inposition by a bracket |88 .and a suitable clamping screw which are inturn supportedI from the underside of insulating panel 21'bysupporting'screw |81 threaded into the bracket.

With the foregoing arrangement' of elements it is seen that uponclockwise rotation of the cam member 18 toward the position assumed inFig. 2,

. the cam surface 18 just strikes the .cam follower this function in thedesired manner a cam follower or roller member 82 is arranged toprotrude f through the slot' 18 from the front side'of thecam member 1-3and is adapted vto be engaged by the cam surface 16 to move the camfollower L 82 in one direction and by the cam surface 11 to move the camfollower in lthe opposite direction when vt cam member is rotated. Camfollower 82 is rigidly secured to the` end of a flexible member orspring leaf 83, the other end of which spring is rigidly fastened to anirregu lar shaped bracket or pivoted lever 84 as may be more clearlyseen in Fig. 5. Bracket lever 84 is pivoted for swinging movement fromthe front of insulating panel 21 upon a pivot pin-88 and an insulatngarm 86 isl rigidiysecured as by screws 81 to the pivoted bracket 84. Inorder to properly calibrate the position of the cam follower 82 withinthe circular slot 18 through which it extends'. an adjusting screw 88isthreaded into lever 84, and by turning this screw 88 in any directionthe proper amount, th'eeamA follower 82 may be centered irnthe slot.

The movable or lower end o'f insulating arm 88 is arranged to carryor`support one of the magnet '|08 while the armature IUI is controlmeans orswitchins .equipment of the device. This switching equipmentdesignated generally as A includes a flat magnetic amature member 88rigidly secured as shown tothe end of Athe insulating member. A pair ofturned up ear portionsof armature 89 form a supportv for a pivot pin 8|upon which a rigid non-mag-I 82 thereby rotatlngbracket 84counterelockwise about pivot pin 88 causing the movement of the lowerend of insulating arm 86 in a. right-hand direction. The armature 89 isthereby moved to a position outside of the magnetic influence of movedwithin the magnetic field and adjacent the poles of the magnet. Thisresults in closing the set of movable contacts 94 and 95 with the xedcontacts 98 and 81 respectively and opening the contact sets |08 and|84. The switching mechanisms A and B are thereby controlled Ysolely bythe rotation of cam member 13 in eitherdirection.

The opening and closing movements of the conf tactA sets is performedwith snap `'action in order to minimize destructive arcing between thecontact sets and toprevent erratic circuit operation, therebyinsuringreliabley and positive performance. This operation is initiatedby the bimetal element I8 being subjected 'l to temperature changes soas to rotate the shaft I9 and the various cam members. The cam followeris there Vby engaged by cam surface 18, for example, and

a certain amountof. tension is gradually stored inthe bimetallic elementI8 as it engages the cam follower 82. 'I'his tension of bimetal elementgradually increases against the magnetic pull of the magnet |88 upon thearmature 8l until a `balance of force between the bimetal element and'the magnet is reached l after which. the bimetal element assumes fullcontrol due to the sudden release 'of its stored energy and the magnetloses its influence over the armature 89. VThe armature I8l, however,has now moved within the mechanism is moving very quickly. 'I'his is dueI to the flexure of the flexible arm maintaining the contacts closed asthe rigid bar moves away from the rea'r of the spaced movable contact.As the contact sets 94-96 and 95-91 engage, the rigid bar 92 engages therear side of contact 35 and the rigid bar acts as a stop to limit themovement of the armature |0| against the magnet and to hold the contactsfirmly in engagement so that theyare -not -affected by vibration orother disturbances. The flexible arm 93 being slightly bowed at thistime a wiping action takes place as the contacts engage and again whenthey open. This also tends to eliminate any bouncing of the contacts asthey engage. Since the rigid bar 92 is pivoted at 8| at its center pointa leveling or equalizig laction of the contact pressure upon both setsof contacts is provided for.- For the same reason, should either set ofcontacts stick or Weld slightly the other set would open to interruptthe circuit and a prying action would take place about the pivot toforce the sticking contacts apart. It is clear that by the use of thebridging bar 92 the use of pig tall or other loose connections for themovable portion of the switching mechanism is eliminated.

lmember 41. The 'cam follower is adapted to be moved in one direction bythe cam surface 53 when the cam member is rotated clockwise,

and moved by the cam surface I9 in the opposite direction then the cammember l1 is rotated counter-clockwise. A relatively flexible arm ||2 isarranged to support the cam follower at one of its ends while at theother end the bar ||2 is rigidly secured to the bracket ||3 which is inl turn pivoted upon a pin III projecting from the panel 21. The bracket||3 is arranged to carry an insulating operating arm ||5. A singlemagnetic armature H6 (Fig. 2) is carried on the lower end of theinsulating arm ||5 and is arranged to be moved into and out of themagnetic influence of the permanent magnet ||1 which is supported uponthe panel 41 in a manner similar to the mounting of magnet Ill. A pairof extending ears i I3 projecting from armature I I6 between the magnetpoles to the other side of the magnet are arranged to carry a pivot'pin||3 at their ends. Pivot pin Il! pivotaliy carries a switching mechanismC arranged in a similar manner to the switching equipment A 'and Bpreviously described. The switching equipment C is adapted to open andclo a set of contact points I 2| and |22 with snap action. Theclocontrol on the' member |21.

sure of the contacts limits the movement of the armature I I5 towardsthe poles of the magnet ||1 in one direction while when the amature ismoved in the opposite direction it strikes an adjustable stop |23carried upon a bracket |24 supported on the insulating panel |21. Themagnet ||1is adapted to hold the contacts in closed position afterhaving once been actuated in that position and in order to maintain themin the open position away from the influence of the magnet, since asecond armature is not provided, an additional holding means is providedcomprising an arm |25 attached to the pivoted bracket 3 and having itsend extending through an opening in the panel |21 to the rear thereof'and a tension spring |26 attached at one end to the arm |25 and theother end to the supporting stud 28. The spring |26 is effective to snapand hold the armature ||6 Vagainst the stop |23. v-From the foregoingarrangement it is seen that the contact switching mechanism C is adaptedto be moved into contact closing position with snap action by the magnet||1 responsive to the movement of cam follower lby cam surface 53 in onedirection, and into contact opening position with snap action by thespring |26 responsive to the cam surface .49 moving the cam follower inthe opposite direction.

A modification of the foregoing switching mechanism is illustrated inFig. 7 which shows a switching mechanism D and E cf a constructionsomewhat similar to the mechanism A andB of Fig. 2. In the switchingmechanism A and B itwill be remembered, both armatures 39 and 'III areconstructed of magnetic material so that they are adapted tobe'influenced by the Imagnet Il! when moved within its magneticinfluence, in order to actuate the contacts with snap action.

- In the switching mechanism C the armature Il! is effective to closethe contact sets in one direction with snap action while the spring |28performs the same function in the opposite direction. In themodification shown the switching mechanism D has its contact structuremounted on a member |21 which is made of nonmagnetic material so thatmagnet I1 will have no'magnetic The other switch structure E, however,is mounted on an armature |28 made of magnetic material. With thisarlrangement when the bracket lever ||3 is pivoted in a clockwisedirection, the member |23 is moved toward the magnet ||1while magneticarmature |23 is moved out of the influence of the magnet. Since member|21 is non-magnetic the magnet cannot hold it in the position in whichit has been moved. To hold the member |21 and its associated switchmechanism in its operated position the tension spring |23 is providedwhich is attached to the spring arm |25. A; a result the cooperatingcontact sets |3| and |32 are snapped contact sets' |3| and |32 areclosed and held.

tightly in that position by the pull 'ofnagnet ||1 upon armature |23while at the same time contact sets |33 and |34 are open.

In order to prevent too great a pivotal movement of the contacts setsabout'their associated pivots such as 3| and |32 which mightinadvertently produce a possible short circuit between two sets ofcontacts mechanisms such as A and B or D and E, slight projections suchas |35 are provided upon the armatures to limit the free pivotingmovement of the rigid arms 82.

In the normal usage of the control device, the /cam members may be setto establish their control function in accordance withy varioustemperature adjustments. For example, as illustrated in the drawings,the cam member 13 is ordinarily adjusted so that the arrow' 15ispositioned opposite a temperature indication of 250 degrees on thescale plate '66. In adjusting the arm 14 it is convenient to grasp thefinger piece -39 with one hand to hold the shaft I9 steady while movingthe adjusting arm 14 with the other hand to rotate the cam member 13.The adjusting arm 56 of the on cam member 55 is then adjusted in thesame controls the low speed operation of the fan, and

the switching mechanism A the high speed operationof the fan. This isdesirable in heating systems where the speed of the fan may becontrolled in response to various temperature values I of the system,rather than have the fan cut in at a. constant speed for a widetemperature range.

In the clockwise movement of the cam members to the position shown inFig. 2, due to the 56. A circuit is thereby completed extending mannerto a position usually at 175 degrees on the A scale 66. The .oif camadjusting arm is adjusted and set to indicate a temperature of usually125 degrees. From the foregoing it is seen that each of the adjustingarms 48, 56 and 14, are preferably arranged in sequential order acrossthe scale plate 66, thereby positioning the associated cam surfaces`49,58 and 16--11 in definite sequence so -that the switching mechanisms C,B and -A are properly operated in sequence and in accordance with thetemperature'settings of the associated indicating. arms. ,Y

Referring particularly to Fig. 1 it will be noted that the adjustingarms 48, 56 and 14 are so formed and arranged as to preclude thepossibility of the adjusting arms overlapping each other and therebycause incorrect operation of the switching mechanism, thus insuring adefinite sequence of switching operations. The stop mem-- ybers 61 and68 on the scale member 63 prevent lthe stops 61'and I68 would be rotateduntil they engaged either the pivot pin 85 or II4. This halts therotation of the elements and prevents the disarrangement ofthe adjustingarms which would otherwise take place by the ends of the circular slots51 and 58 engaging the cam followers 82 and III respectively, `androtating the cani members against the friction washers.. It

from `the hot side of the line through the contact sets I2I-I22 oftheswitching mechanism C, contacts ID3-I 04 of the switching mechanism B,through the lowl speed winding of the'fan motor to the "grd or groundside of the line. At the temperature of 175 degrees, therefore, the fanis operated at low speed to force the heated air throughout the premiseslbeing `heated by the system. As the temperature gradually increases, vatemperature point` of 250 degrees is eventually encountered as indicatedby the arrow 15 for the adjusting arm 14. At this temperature point thecam surface 16 engages cam follower 82, and as a result the switchingkmechanism B snaps openl the' contacts IUS- |04 and the switchingmechanism A closes contacts 94-96 and 85-91. This results in thetransfer of they circuit from the low speed winding of the fan motorover to the high speed portion, and the increased speed of the fan isenabled to circulate the higher heated air more. rapidly. The bimetalelement may continue to be heated beyond 250 degrees and the fanconsequently operates at its high speed.

t It will -be understood, of course, that the cir-,- cuit arrangementdescribed is incorporated in a heating system involving otherinstrumentalities, such as suitable burners, room thermostat, etc. Whenthe room thermostat has been satisfied and cut oif the heat from thefurnace, the tempera- Y tate the cam members in a counter-clockwise divrection.

will be observed that the arrow 39 onl the finger piece 38 cooperatewith the temperature scale 40 (Fig. 6) stamped upon the front of cover24 to at all times indicate the correct temperature of the mediumsurrounding the bimetal elementji.

The control device as illustrated in the drawings is arranged to show a.partial operated position in'that the bimetal element I6 is under theinfluence of a temperature value of about 200 degrees as indicated bythearrow 38 and the cover scale 40. Therefore, the switching mechanisms A,B and C have been shown actuated in a particular sequential manner.

Referring now to Fig. 8, therel is disclosed a schematic circuitarrangement depicting one of Ithe uses for the control device as a partof a heating system.l In this arrangement a two-speed fan motor is shownwired so that the switching Ill) Eventually a temperature point of 250degrees or less is reached depending upon the fixed differential betweenthe cam surfaces v16 and 11. 'I'he cam surface 11 thereby engages camfollower 82, with the result that the switching mechanism A snaps openits contacts and mechanism B vcloses its contacts again so that the fanis now operated at the lower temperature value. This low speed lof thefan continues for a time until the temperature recedes to a. value of125 degrees, as indicated by the adjustment of th "oi cam adjusting arm48. When this point is encountered cam surface 49 engages cam followerIll to snap open the contact sets I2I'-I22 of the. switching mechanismC. As a result the operation of the fan motor is stopped. The bimetalelement I6 continues to gradually cool off as the heat in thevfurnace isdissipated,

until it reaches the temperature of the Yambient dual heat existingr inthe furnace to which the control device is attached.- The control deviceis now in its normal inactive position of rest.

It will be noted that the cam member 13 has its cam surfaces 16--11formed on opposite sides of the circular slot 18. With this arrangementthe'cam follower 482, is always actuated in one direction by the camsurface 16 at the particular temperature value indicated by the arrow onthe scale plate 58 and in the other direction by the cam surface 11 at atemperature value of a few degrees lower for example. Therefore a fixedoperating differential for the cam follower4 82 is provided. The slotedges extending from each side of the cam surfaces permits the continualrotation of the cam member 13 in either direction without straining theswitching mechanism, since the cam follower rides along in the slot 18.A form of lost motion"connection is thereby provided for the elements.The switching mechanism C, however, in which the cam follower lil iscontrolled by the two cam surfaces 48 and 58, is arranged with anadjustable differential. The cam surface 58 actuates the switchingmechanism C at .one temperature, while the carr surface 49 actuatcs theswitching mechanism C at another ory lower temperature point', andmoving the adjusting arms 48 andk 58 .closer together on the scale platenarrows the differential, while moving them apart widens thedifferential or operating point between the cutin and the cut-out pointat which the switching mechanism is operated.

It may be desirable during the summer months, for example, when theheating plant is shut down, to operate the fan motor to circulate coolair throughout the premises. To accomplish this, the nger piece 38 ofthe knob 31 is grasped and manually rotated clockwise against thetension exerted by bimetal I8 until a position is reached in which thenotch 42 (see Fig. '1) registers with or is in'alignment with the pin 43on the panel 21. At this point the knob 31 is then pushed slightlyinward until the pin an'd notch engage, whereupon the knob is released.The energy stored in the bimetal I6 is suihcient to hold the edge ofnotch 42 in engagement with the head of pin 43 and the cam elements arethereby locked in position until manually released. In the lockedposition the switching mechanism C has its contacts locked closed,switching mechanism B open, and switching mechanism A closed. 'l'he fanmotor is thereby .continually operated at a high speed to circulate the.cooling air throughout the premises.

Under certain conditions the burner may be arranged to start operationwith the control locked in manual operative position in which event thebimetal I6 would be heated up until an elevated temperature point isencountered, for example 250 degrees, and which is. also the position atwhich the notch 42 is opposite pin 43. `Whenthis occurs` the manuallocked setting is released and the control is restored automatically toits automatic operation.

In the circuit arrangement of Fig. 8 it will be noted the contacts ID3and 96 are strapped together. With the wiring arranged in this mannerthe possibility `of a short circuit occurring through the armaturebetween adjacent sets of contact sets A and B is avoided.

Referring now particularly to Fig. v9', this shows a schematic circuitdiagram involving a fan motor and a burner, and a room thermostat T ,hasalso been indicated. In this arrangement the fan motor is controlled bythe switching mechanism C while the burner is controlled by theswitching mechanism B connected in parallel with the fan motor andswitching mechanism C. In the operation of this arrangement theswitching mechanis'm B functions asla high limit control to dis--lconnect the burner when'a temperature of 250 degrees, as indicated bythe setting of the cam member 13, is encountered. The fan motor is cutinto operation when a temperature of 175 degrees is encountered and cutout again when a temperature of 125 degrees is reached. The thermostat Tis operative to start the burner upon a call for heat so that thebimetal element i5 will be subjected to the rise in temperature tooperate the control device in its proper sequence, as has been pointedout.

In.certain localities to prevent overheating of the furnace it isrequired that the switching mechanism B be so arranged that it cannot beadjusted to operate above a particular high temperature value. For thispurpose the stop screw 19 is arranged in one of the screw holes in cammember 13 so as to engage the end of slot 8l in scale member 63 andprevent the adjustment of adjusting arm 14 to a temperature point beyondthe range of 250 degrees for example.

If it is desired to operate the fan motor in the summer months forcooling purposes, the knob 31 may be manually rotated to lock the camelements in position as has been pointed out. In this position theswitching mechanism C is locked with its contacts closed to run the fanmotor, and the thermostat T must be adjusted to maintain its contactsclosed. The switching mechanism B is locked open and prevents theoperation of the burner under these conditions.

From the foregoing description it will be appreciated that a novelcontrol' mechanism has been devised which is extremely simple inoperation; in which the switching mechanisms are reliably operated insequential order without possibility of overlapping the control points;in which adjustments are readily made; and in which several seis ofswitching mechanisms may be operated through the function of a singlebimetal element.

While only one preferred embodiment of the invention with twoalternative switch mechanisms have been illustrated and described, itwill be apparent that any number of modifications or deviations from theexact structure described may be made by those skilled in the art, andit is to be understood that the invention is not limited to theparticular disclosure, but only by the extent of the scope of theappended claims.

What is claimed is:

1. In a control device, a hub member, means for effecting rotationalmovement of said hub member in either of two directions, an indicatingscale member rigidly secured to the hub member and rotatable therewith,a pair of adjustable cam members arranged on the hub member on one fspect to thescale member is afforded, separate control means arranged tobe operated by the rotation of said pair of cam members and byf saidsingle cam member, and cooperating indicating means on al1 of said cammembers and said scale member for indicating the adjusted position ofcondition responsive means for rotating said hub member in either of twodirections, a switch operating member, a rst and a second cam memberarranged on said hub member, means on the ilrst cam member for actuatingthe switch member in one direction -upon the rotation of the hub memberin one direction, means on the second cam member for actuating theswitch member in another direction upon rotation of the hub member inthe opposite direction, an indicating disc rigidly Asecured to the hubmember, yieldable means on said hub member for holding said cam membersagainst one side of said indicating disc so as to be normally movabletherewith, friction means on said hub member between the cammembers andindicating disc whereby adjustment of the cam members on the hub memberis ail'orded to vary the operating point at wliicl'ithe switch member isactuated by the cam members, a third cam member arranged on the hubmember, a second switch operating member, means on the third cam memberfor actuating the secfirst control means actuated by the rotation ofsaid single cam member, said single cam member ond switch member ineitherl of two directions upon rotation of the hub member, a secondyieldable means on the hub member for holding said i, third cam againstthe other side of the indicatside ofthe scale member, a single cammember l on the hub member arranged o`n the other side of the scalemember, means for yieldably' urging all of said cam members against saidscale member so asto be rotatable therewith, means frictionally engagingsaid cam members' and said scale member, an adjusting arm on each cammember for variably adjusting the associated cam member against saidfriction means, cooperating adjustment indicating means on the scalemember and said adjusting arms, and separate control means operated bysaid pair of cam members and said single cam member.

5. In a control device, a hub member, means for eecting rotationalmovement of said hub member in either, of two directions, a scale memberrigidly secured lto said hub`member and rotatable therewith, a pair ofcam members on the hub member arranged on one side of the scale member,a single cam member on the -hub member arranged on the opposite side ofthe scale member, means on the hub memberfor frictionally holding all ofsaid cam members against said scale member so as to be rotatable,ltherewith,

y adjusting means on eachof said cam members for adjusting the positionlof the associated cam member against the friction'holding means, a

provided with a fixed control operating differential, a second controlmeans actuated by the rotation of said pair of cam members, said pair ofcam members cooperating to provide a variable control operatingdifferential, and stop means on said scale member for limiting the rangeof adjustment oi said adjusting means.

6. In a control device, a hub member, temperature responsive means forrotating said hub member in either of two directions, a scale memberrigidly secured to the hub member and rotatable therewith, cam memberson the hub member arranged on opposite sides of the scale member, meanson the hub member for fr ictionally holding said cam members againstsaid scale member so as to be rotatable therewith, an adjusting arm `oneach cam member for adjusting the position of the cam member against thefriction holding means, stop means on the scale member for limiting therangevof adjustment of one of the adjusting arms, said cam membershaving a circular slot formed therein with a cam surface on the sides ofthe slot,a cam follower in the slot of each cam member arranged to beactuated by the cam surface upon the rotation of the associated cammember, control means connected to the cam followers and actuated by themovement thereof, and other stop means engageable by the scale memberfor limiting the rotation of the hub member beyond a xed range wherebythe ends of the cam slots are prevented from engaging the cam followersand disturbing the adjusted setting of the adjusting arms in the eventthat the effort of the temperature responsive means is abnormallyexcessive.

'7. In a control device, a rotatable hub memvber, adjustable cam meanscarried upon the hub member and rotatable therewith, switch controlmeans operated by the cam means, physical condition responsive meansconnected to said hub member for rotating thesame to effectthe actuationof said switch control means, manual means on the hub member to effect'the f actuation of said switch control means independently of theoperation-of the physical condition responsive means, and means forlocking said switch control means in the actuated position only whenactuated by the manual means.

8., In a control -device, a rotatable hub member, a cam memberadjustably supported ony said hub member, switch control means, meansvon said cam member for operating the switch control means upon the hubmember being rotated an adjustable predetermined distance, a c

resilient temperature responsive element connected to one end of the hubmember for eect- Aing rotation of the hub member land thereby iency 'ofsaid temperature responsive, element maintaining said locking meanseffective.

`9. In a control device, a rotatable hub member, a cam member adjustablycarried on said hub member, switch control means, said switch controlmeans actuated by the cam member upon the rotation of therhub member toa predetermined position, reslient temperature 'responsive meansconnected to said hub member for effecting rotationl of said hub memberwithin a normal operating range including said predetermined position, aknob member connected to said hub member for manually rotating the hubmember beyond the operating range in opposition to the resiliency of thetemperature re- ;sponsive element to operate the switchcontrol lmeansindependently of the temperature responsive means, locking meanscontrolled by the knob member for locking the hub member and thereby theswitch control means in operated po'\l sition, the resiliency of thetemperature responsive means cooperating with said locking means to holdthe switch, control means in locked position, and said temperatureresponsive means acting when heated beyond`said range to automaticallyrelease said locking means.

10. In a control device', a hub member, temperature responsive means foreffecting rotational movement of said hub. member in either of twodirections, a scale member rigidly secured to the hub member androtatable therewith, a plurality of cam members on the hub memberarranged on opposite lsides of the scale mem- .tions, said-contacts.being operated with snap action produced by the conjoint action of saidmagnet and armature and the resiliency of said temperature responsivemeans.

ber, means on the hub member for frictionally holding all of said cammembers against said scale member so as tov be rotatable therewith, anadjusting arm on`each cam member for adi justing the position of theassociated cam member against the friction holding means, stop means onthe scale member for 'limiting the range of adjustment of said adjustingarms, a separate control means actuated by each of said cam members at apoint dependent upon the adjusted position of the associated cam member,manually operated means on the hub member for rotating the hub memberindependently of the temperature response means and for locking the hubmember in its rotated position whereby `the control means are locked ina selected operated position, said manually operated meanslockingsaidhub member in position at a point beyond the normal operating range atwhich it is actuated by the temperature responsive means.

11. In a control device, a physical condition responsive means havinginherent resiliency, an adjustable cam member arranged to be operated bysaidphysical condition responsive means, a cam follower, said cam memberhaving a slot therein through which said cam follower extends wherebysaid cam follower is operated in either of two directions as the cammember is operated, pivoted switching mechanism, and lever meansconnecting the cam follower with the switching mechanism for operatingthe same,

` said switching mechanism comprising; a pair of e armatures connectedto the lever means and a magnet arranged between the two armatures,pairs of movable contacts, means for 'pivotally supporting a pair ofmovable contacts from each armature, a pair of xed contacts arranged inoperable relation to the movable contacts, the

resiliency of said physical \condition responsive means cooperating withsaid armatures and magnet to eilect the operation`of said contacts withsnap action. n

12. In a control device, a temperature responsive element havinginherent resiliency, an adjustable cam member arranged to be rotated ineither of two directions by said temperature responsive means, acam'follower arranged to be operated by said cam member, and switchingmechanism controlled by the operation of said 13. In a control device,switching mechanism, an' actuator member for said switching mechanism,said switching mechanism comprising a pair of armatures secured tosaidactuator member and movable thereby, a magnet arranged between thepair of armatures and eifective to exert la magnetic snap action andholding force upon either armature when moved into close proximitythereto, separate bridging bars one for each armature, each bridging barbeing pivoted at its center to the corresponding amature and havinglimited pivotal movement, pairs of spaced movable contacts carried bysaid bridg-- ing bars and pairs of fixed contacts arranged inoperativerelation with corresponding pairs of movable contacts, the pivotalarrangement of said bridging bars providing equal contact pressure uponthe closed pairs of contacts when the associated armature is under theinfluence of the magnet, and the fixed contacts acting asstops armaturesand arranged to attract. with snap action and hold either armature whenmoved into the influence of the magnet by the pivoted lever, the otherarmature at the same time being moved away from the magnet, separatebridging bars freely pivoted at their mid-points to the sides of thearmatures away from the` magnet, pairs of movable contacts carried onthe ends of the bridging bars, corresponding pairs of fixed contactsarranged in cooperative relationship with the pairs of movable contacts,each bridging bar effective to establish a closed circuit series pathincluding corresponding pairs of fixed and movable contacts and thebridging bar when the said pairs of contacts are closed responsive tothe attraction of the armature associated with the other pairs ofcontacts, the pivoted bridging bars providing for equal pressure `uponthe pairs of closed contacts. and the fixed contacts serving as stops tolimit the attraction of the armatures towardsY the magnet.

15. In a control device, a physical condition responsive means, apivoted operating lever, a cam member controlled by said physicalcondition responsive means for actuating said operating lever in eitherof two directions about its pivot, and switching mechanism operated bysaid pivoted lever, said switching mechanism' comprising; an armatureand a non-magnetic member arranged in spaced parallel relationship andattached to the pivoted lever, a magnet disposed between the armatureand the non-magnetic member and arranged to magnetically snap and holdthe armature adjacent the magnet when moved into its innuence bythepivoted lever, a spring for snapping and holding the non-magnetic membertoward the magnet while at the same time the armature is snapped awayfrom the magnet, separate contact bridging bar's one freely pivoted tothe armature and another freely pivoted to the non-magnetic member,pairs of movable contacts carried by the bridging bars, pairs of fixedcontacts supported. in operative relation with corresponding pairs ofmovable contacts, said contacts arranged so that the closure of a pairof contacts establishes a series circuit path through the movable andxed contacts and the associated 4bridging bar, the pivoting arrangementof the bridging bars providing for equal contact pressure upon eitherclosed pair of contacts when the armature is snapped within the holdinginfluence of the means arranged on said base member on the other side ofsaid indicia structure, adjustingv means associated with said first cammeans for adjusting the angular position of said first cam `one side ofsaid indicia structure, a second cam means on said base member, meansshifted with I said rst came means and cooperating with said indiciastructure for indicating the setting of the tlrst cam means on said basemember, adjusting means associated with said second cam means foradjusting its angular position on said 'base member, means shifted withsaid second cam means and cooperating with said indiciastructure forindicating the setting of said second cam means, and controlmeansactuated by said first and second cam means. 17. In a controldevice, a rotatable base member, an indicia structure mounted upon saidbase member and arranged to rotate therewith, a first cam means arrangedon said base member on one side of said indicia structure, a second cammeans arranged on said base member on the other side of said indiciastructure, spring and friction means for yieldably urging said first andsecond cam means intofrictional engagement with said indicia structureso as nor-'- mally to rotate therewith, a manual adjusting handleassociated with said ilrst cam means for adjusting the angular positionof said rst cam means on said base member, means shifted with said firstcam means and cooperating with said indicia structure for indicating thesetting of the rst cam means on said base member, a manual adjustinghandle associated with the second cam means for adjusting its angularposi .tion on said base member, means shifted with said second cam'means and cooperating with said indicia structure for indicatingthesettlng of said second cam means, and control means actuated by saidfirst and second cam means.

1 8. In a control instrument for a heater, a resilient temperatureresponsive means adapted to respond to the temperature of the heater, acontroller adapted to control the temperature of the heater, motiontransmitting means between said temperature responsive means and saidcontroller for causing movement of said controller in accordance withchanges' in temperature at said temperature responsive means, a manualcontrol member for manuallyoperating said controller to troller in saidpredetermined position, the resiliency of the temperature responsivemeans cooperating with the locking means to hold the controller in saidpredetermined position, and said temperature responsive means actingwhen heated beyond a predetermined value to release said locking means.

19. In a control device, switching mechanism, an actuator member forsaid switching mechanism, said switching mechanism comprising a pair ofarmatures secured to said actuator member and movable thereby, magnetmeans associated with said armatures and effective to exert a magneticsnap action and holding force on either armature when moved into closeproximity thereto, separate bridging bars one for each armature, eachbridging bar being pivoted at its center to the corresponding armatureand having limited pivotal movement, pairs of spaced movable contactscarried by said bridging bars and. pairs of fixed contacts arranged incooperative relationship with corresponding pairs of said movable'contacts, the pivotal arrangement of said bridging bars providing equalcontact pressure upon the closed pairs ofcontacts when the associatedarmature is under the influence of the magnet means, and the xedcontacts acting'as stops to prevent the actual engagement of thearmatures with the magnet means.

20. In a control device, switching mechanism, an actuator member forsaid switching mechanism, said switching mechanism comprising armaturemeans secured to said actuator member and movable thereby, magnet meansassociated with said armature meansand arranged to exert an increasingmagnetic pull on said armature means upon movement thereof in onedirection to impart snap action 'to said movement, said magnet meansalso arranged to exert an increasing magnetic pull on said armaturemeans in the opposite direction upon movement thereof in said oppositedirection, a first bridging bar pivotally secured intermediate its endsat one side or said armature means and carrying a pair of spacedcontacts, a pair of fixed contacts in cooperative relationship with saidpair of movable contacts, a second bridging bar pivotally securedintermediate its ends at the other side of said armature means, a pairof ilxed contacts in cooperative relationship with the last mentionedpair of movable contacts, the pivotal arrangement of said bridging barsproviding equal contact pressure upon the closed pairs of contacts andthe fixed contacts acting as stops to prevent actual engagement of thearmature means with the magnet means.

21. In a control device, a rotatable member, control means actuated fromone position lto another .by rotation of said member, resilientcondition responsive means for rotating said rotatable member, manualmeans for rotating said rotatable member independently of and againstthe resiliency of said condition responsive means to cause said controlmeans to assume a predetermined one of its positions irrespective of thevalue of the condition to which the condition responsive means responds,and means for retaining the control means in such predetermined positionafter the manual means is released.

22. In a control device, a rotatable member, control means actuated fromone position to another by rotation of said member, resilient conditionresponsive means Afor rotating said rotatable member, manual means forrotating said rotatable member independently of and against theresiliency of said condition responsive means to cause said controlmeans to assume a predetermined one of its positions irrespective of thevalue of the condition to which the conditionresponsive means responds,and means for retaining the control means in such predetermined positionafter the manual means is released, said retaining means including astationary latch member and a movable latch member arranged to be heldinengagement by the resiliency of the condition responsive means.

CERTIFICATE OF CORRECTION.

Patent No., 2,515,555. Apr-11 6, 19u5.

HOHER E. mLoNE.

It is hereby certified that error appears in the printed specificationof the above nlmbered patent requiring correction as follow-s: Page8,1`irst column, .line 8, claim 9, for "element" read -'means; and thatthe said Letters Patent should be read with this correction therein thatthe same .may conform to the record of the case in the Patent Office.

Signed and sealed this 9th day of November, A.. D. 19115. f

Henry Van Arsdale, (Seal) Acting Commissioner of' Patents.

CERTIFICATE OF CURRECTION.

Patent No.Y 2,515,555. April 6, 19u5.

norma E. mLoNE.

It is hereby certified that error appears in the printed specificationof the above nfmbered patent requiring correction as follows: Page8,first column, .line 8, claim 9, for "element" read =meansg and thatthe said Letters Patent should be read with this correction therein thatthe same may conform to the record of the case in the Patent Office.

signed and sealed this 9th day of Nevember, A, D. 191g.

Henry Arsdale, (Seal) Acting Commissioner of Patents.

